scholarly journals Variations on the larval incubation of Anodontites trapesialis (Unionoida, Mycetopodidae): Synergetic effect of the environmental factors and host availability

2012 ◽  
Vol 72 (3) ◽  
pp. 545-552 ◽  
Author(s):  
CT. Callil ◽  
D. Krinski ◽  
FA. Silva
Keyword(s):  
Environmental Factors ◽  
Temporal Variation ◽  
Environmental Variables ◽  
Freshwater Mussels ◽  
Synergetic Effect ◽  
Flood Pulse ◽  
Host Availability

The unionid Anodontites trapesilais (Lamarck, 1819) like most freshwater mussels is a parasite of fish. So it is trivial to assume that the availability of hosts is an important factor for the maintenance of unionoid populations. What seems obvious is not always so easy to demonstrate. This study proposes to investigate the effects of abiotic and biotic variables related to the incubation of larvae in A. trapesialis. For this, we estimate different biological indexes and try to capture the dimensionality of the fish, along with the temporal variation of environmental variables. From the application of a CCA, it was demonstrated that there was a synchronicity among the factors and variables proposed here, and we infer that the flood pulse acts as a synergistic factor in this process.

scholarly journals Distribution Patterns of Odonate Assemblages in Relation to Environmental Variables in Streams of South Korea

Insects ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 152 ◽  
Author(s):  
Da-Yeong Lee ◽  
Dae-Seong Lee ◽  
Mi-Jung Bae ◽  
Soon-Jin Hwang ◽  
Seong-Yu Noh ◽  
...  
Keyword(s):  
Land Use ◽  
Ecosystem Services ◽  
Environmental Factors ◽  
South Korea ◽  
Habitat Heterogeneity ◽  
Environmental Variables ◽  
Environmental Changes ◽  
Distribution Patterns ◽  
Self Organizing Map ◽  
Factors Affecting

Odonata species are sensitive to environmental changes, particularly those caused by humans, and provide valuable ecosystem services as intermediate predators in food webs. We aimed: (i) to investigate the distribution patterns of Odonata in streams on a nationwide scale across South Korea; (ii) to evaluate the relationships between the distribution patterns of odonates and their environmental conditions; and (iii) to identify indicator species and the most significant environmental factors affecting their distributions. Samples were collected from 965 sampling sites in streams across South Korea. We also measured 34 environmental variables grouped into six categories: geography, meteorology, land use, substrate composition, hydrology, and physicochemistry. A total of 83 taxa belonging to 10 families of Odonata were recorded in the dataset. Among them, eight species displayed high abundances and incidences. Self-organizing map (SOM) classified sampling sites into seven clusters (A–G) which could be divided into two distinct groups (A–C and D–G) according to the similarities of their odonate assemblages. Clusters A–C were characterized by members of the suborder Anisoptera, whereas clusters D–G were characterized by the suborder Zygoptera. Non-metric multidimensional scaling (NMDS) identified forest (%), altitude, and cobble (%) in substrata as the most influential environmental factors determining odonate assemblage compositions. Our results emphasize the importance of habitat heterogeneity by demonstrating its effect on odonate assemblages.

scholarly journals Geographically weighted regression modelling of the spatial association between malaria cases and environmental factors in Cameroon.

2020 ◽  
Author(s):  
Marlvin Anemey Tewara ◽  
Liu Yunxia ◽  
Weiqiang Ling ◽  
Binang Helen Barong ◽  
Prisca Ngetemalah Mbah-Fongkimeh ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Spatial Variability ◽  
Geographically Weighted Regression ◽  
Environmental Variables ◽  
Vegetation Index ◽  
Spatial Association ◽  
Ordinary Least Squares ◽  
Variable Coefficients ◽  
Weighted Regression ◽  
Gwr Model

Abstract Background: Studies have illustrated the association of malaria cases with environmental factors in Cameroon but limited in addressing how these factors vary in space for timely public health interventions. Thus, we want to find the spatial variability between malaria hotspot cases and environmental predictors using Geographically weighted regression (GWR) spatial modelling technique.Methods: The global Ordinary least squares (OLS) in the modelling spatial relationships tool in ArcGIS 10.3. was used to select candidate explanatory environmental variables for a properly specified GWR model. The local GWR model used the global OLS candidate variables to examine, predict and explore the spatial variability between environmental factors and malaria hotspot cases generated from Getis-Ord Gi* statistical analysis. Results: The OLS candidate environmental variable coefficients were statistically significant (adjusted R2 = 22.3% and p < 0.01) for a properly specified GWR model. The GWR model identified a strong spatial association between malaria cases and rainfall, vegetation index, population density, and drought episodes in most hotspot areas and a weak correlation with aridity and proximity to water with an overall model performance of 0.243 (adjusted R2= 24.3%).Conclusion: The generated GWR maps suggest that for policymakers to eliminate malaria in Cameroon, there should be the creation of malaria outreach programs and further investigations in areas where the environmental variables showed strong spatial associations with malaria hotspot cases.

scholarly journals Dinámica de la estructura y composición de macroinvertebrados y su relación con las variables ambientales en la bahía de Buenaventura

2018 ◽  
Vol 47 (1) ◽  
Author(s):  
Diego Esteban Gamboa-García ◽  
Guillermo Duque ◽  
Pilar Cogua
Keyword(s):  
Regression Analysis ◽  
Temporal Variation ◽  
Multiple Regression Analysis ◽  
Multiple Regression ◽  
Environmental Variables ◽  
Physicochemical Variables ◽  
Descriptive Information ◽  
Three Samples

Buenaventura bay is characterized by a great dynamic of environmental variables. There is descriptive information concerning the distribution of macroinvertebrates in the bay and its habitat, however it is necessary to document on its dynamics in relation to environmental variables. The objective of the present work was to determine the espatio-temporal variation in the structure and composition of macroinvertebrates and their relationship with the environmental variables. Four sampling (April-June-September-November) were carried out throughout 2015, in four stations (Estuary River-Internal Estuary-External Estuary-Marine Estuary). At each station three samples of sediments, physicochemical variables of the water and macroinvertebrates were collected. A total of 532 individuals were found in 17 species and 9 families. The abundance varied from 0.7±1.2 to 29.7±7.4 individuals per trawl and the richness varied from 0.3±1.2 to 4.7±1.2 species per trawl. The multiple regression analysis suggests an influence of the variables salinity and percentage of clayson the structure and composition of macroinvertebrates in the bay. The abundance and richness of macroinvertebrates was higher when the salinity conditions prevailed in the estuary.

scholarly journals Longitudinal and seasonal succession of algal periphyton colonization in lowland river (Tundzha River Part of Turkey)

2016 ◽  
Author(s):  
Burak Öterler
Keyword(s):  
Environmental Factors ◽  
Dissolved Oxygen ◽  
Green Algae ◽  
Environmental Variables ◽  
Diversity Index ◽  
Seasonal Succession ◽  
Lowland River ◽  
Blue Green Algae ◽  
Periphytic Algae ◽  
Wiener Diversity Index

The aim of this paper is to determine and compare the environmental factors controlling longitudinal colonisation of periphytic algae in agricultural and urbanization effects of a lowland river, the Tundzha River, located in Turkish Tunca. To investigate the effect of the environmental factors on periphyton colonization at the river, 6 stations were selected and samples were collected between April 2012 and March 2013. Canonical correspondence analyses have been applied to clarify relationships between environmental variables and periphytic algae. During the study, the Shannon-Wiener diversity index (H′) varied from 1.62 to 3.91. The phytoplankton biovolume was positively related to pH, temperature, salinity, chlorophyll- a and nutrients, and was negatively correlated with dissolved oxygen, turbidity, and silicate. Out of the 5 divisions and of 73 identified species of phytoplankton, the diatoms, namely Fragilaria ulna, Cymbella tumida, Cocconeis placentula, Gomphonema acuminatum and Cymbella cystula were found to be dominant. In addition to these species, the biovolumes of filamentous diatom Melosira varians, filamentous blue-green algae Oscillatoria limosa, and placcoderm desmids Cosmarium botrytis were determined to be at high levels during the year. The euglenoid blooms in St.5 showed many times during the study period.

scholarly journals Longitudinal and seasonal succession of algal periphyton colonization in lowland river (Tundzha River Part of Turkey)

2016 ◽  
Author(s):  
Burak Öterler
Keyword(s):  
Environmental Factors ◽  
Dissolved Oxygen ◽  
Green Algae ◽  
Environmental Variables ◽  
Diversity Index ◽  
Seasonal Succession ◽  
Lowland River ◽  
Blue Green Algae ◽  
Periphytic Algae ◽  
Wiener Diversity Index

The aim of this paper is to determine and compare the environmental factors controlling longitudinal colonisation of periphytic algae in agricultural and urbanization effects of a lowland river, the Tundzha River, located in Turkish Tunca. To investigate the effect of the environmental factors on periphyton colonization at the river, 6 stations were selected and samples were collected between April 2012 and March 2013. Canonical correspondence analyses have been applied to clarify relationships between environmental variables and periphytic algae. During the study, the Shannon-Wiener diversity index (H′) varied from 1.62 to 3.91. The phytoplankton biovolume was positively related to pH, temperature, salinity, chlorophyll- a and nutrients, and was negatively correlated with dissolved oxygen, turbidity, and silicate. Out of the 5 divisions and of 73 identified species of phytoplankton, the diatoms, namely Fragilaria ulna, Cymbella tumida, Cocconeis placentula, Gomphonema acuminatum and Cymbella cystula were found to be dominant. In addition to these species, the biovolumes of filamentous diatom Melosira varians, filamentous blue-green algae Oscillatoria limosa, and placcoderm desmids Cosmarium botrytis were determined to be at high levels during the year. The euglenoid blooms in St.5 showed many times during the study period.

Environmental factors responsible for shaping an open peatland – forest complex on the hypermaritime north coast of British Columbia

2003 ◽  
Vol 33 (12) ◽  
pp. 2380-2394 ◽  
Author(s):  
Taro Asada ◽  
Barry G Warner ◽  
Jim Pojar
Keyword(s):  
British Columbia ◽  
Environmental Factors ◽  
Plant Communities ◽  
Environmental Variables ◽  
Groundwater Table ◽  
North Coast ◽  
Minimum Level ◽  
Peat Accumulation ◽  
Upland Forest ◽  
Vegetation Gradient

The relationships between the distribution of plant communities and environmental factors were studied in an open peatland – forest complex of the hypermaritime north coast of British Columbia. The entire vegetation gradient, from open through forested peatlands to upland forest, was primarily explained by slope and minimum level of groundwater table. Environmental conditions in the upland Tsuga–Rhytidiadelphus forest were considerably different from those of the other communities; differences were small among the Sphagnum open peatland, the Pinus–Sphagnum woodland, the Chamaecyparis–Fauria forest, and the Thuja–Gaultheria forest. Highest level of groundwater table, conductivity minimum, pH, and dissolved oxygen merely helped distinguish the upland Tsuga–Rhytidiadelphus forest from all other communities. The wet Thuja–Gaultheria forest could be more vulnerable than the upland Tsuga–Rhytidiadelphus forest to local hydrological changes caused by harvesting. Consecutive intraannual measurements of environmental variables are important in clarifying the relationships between distribution of plant communities and environmental variables, especially for communities with peat accumulation.

scholarly journals Temporal variation in the effects of individual and environmental factors on nest success

The Auk ◽  
2018 ◽  
Vol 135 (2) ◽  
pp. 326-341 ◽  
Author(s):  
Merle D. Crombie ◽  
Peter Arcese
Keyword(s):  
Environmental Factors ◽  
Temporal Variation ◽  
Nest Success

Identification of key environmental variables associated with the presence of Toothed Leionema (Leionema bilobum serrulatum) in the Strzelecki Ranges, Victoria, Australia

2011 ◽  
Vol 59 (3) ◽  
pp. 207
Author(s):  
Wendy Wright ◽  
Xuan Zhu ◽  
Mateusz Okurowski
Keyword(s):  
Environmental Factors ◽  
Habitat Suitability ◽  
Rare Species ◽  
Environmental Variables ◽  
Geographical Information Systems ◽  
Predictive Modelling ◽  
Geographical Information ◽  
Suitable Habitat ◽  
Small Tree ◽  
Disturbed Areas

Toothed Leionema is one of four subspecies of Leionema bilobum from the Rutaceae family. A dense shrub or small tree, growing to ~4 m high, it is a poorly investigated species which is considered rare in Victoria, Australia. This paper presents the results of a study using Geographical Information Systems and Weights-of-Evidence predictive modelling to assess the importance of seven environmental factors in determining habitat suitability for this species in the Strzelecki Ranges, Victoria. This method is particularly useful in understanding the distribution of rare species, especially where the ecology of the species of interest is not well understood. Of the seven environmental factors considered here, four were found to be important: elevation, aspect, distance to water and distance to plantation (disturbed) areas. The modelling results indicate that areas with elevations between 350 and 550 m and a dominant south-western aspect that are close to plantation areas (within 700 m), and to water (within 1100–1200 m), provide potentially suitable habitat for Toothed Leionema in the region.

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